Such apparatus are generally known. In this respect, so-called optical scales are frequently also used with such apparatus and comprise at least one camera which is attached in front of the cutting compartment and which acquires the cross-sectional surface of a product which is visible from the front in the product compartment. The product cross-section appears light and the environment or hollow spaces in the product appear dark. A good contrast is important for the acquisition quality in this respect. A signal to the slicer control is generated by the evaluation of the images. The classification of the number of slices and of the slice thickness can thus be carried out or corrected in accordance with the recognized holes in a loaf of cheese, for example, to achieve the desired weight of a portion. An image of the end face of the product is thus generated and indeed in a narrow time window in which the cutting surface is completely freely visible. This is a point in time in this respect at which the cutting blade is still just located outside the cutting surface and the previously cut off slice is completely placed down. To avoid total reflections such as white spots, which would prevent an image evaluation, it was previously avoided to illuminate the product cross-sectional surface from the end face.
It has also already been proposed to illuminate as much of the total region of the cutting surface as possible from below with sidelight by means of a lamp inserted in the optical scales. The installation position of the lamp provided for this purpose, however, frequently causes technical application problems and disadvantages in operation. A specific gap is thus required between the portioning belt and the cutting edge for a secure light passage from below, for which purpose the portioning belt has to be arranged relatively low. However, this now brings about a relatively large drop height which is disadvantageous for the placing down. In addition, on a lighting from below, the cast shadow of the falling slices has to be observed since this has a substantial influence on the time window available for a shot. Furthermore, a cast shadow can arise in the sidelight due to a so-called projection formation at the lower side of the product, that is in the region of the contact at the cutting edge. In this respect, a shadow falls in the above-disposed surface regions, which can make the evaluation substantially more difficult.